Fuel injection apparatus for internal combustion engines

ABSTRACT

In a fuel injection apparatus in which the terminal moment of the injection during each pressure stroke of the pump piston is determined in an engine rpm-dependent manner by the position of the governor member of a centrifugal governor, the beginning moment of each injection is determined by a setting mechanism which is responsive to the output pressure of a fuel pump serving the fuel injection apparatus. Said output pressure, in turn, is a function of the position of said governor member.

United States Patent [1 1 Laufer [451 Sept. 23, 1975 1 1 FUEL INJECTION APPARATUS FOR INTERNAL COMBUSTION ENGINES [75] Inventor: Helmut Laufer, Stuttgart, Germany [73] Assignec: Robert Bosch G.m.b.H., Stuttgart,

Germany [22] Filed: Nov. 24, 1972 [21] Appl. N0.: 309,009

[30] Foreign Application Priority Data Nov. 26, 1971 Germany 2158689 [52] US. Cl. 123/139 AP; 123/139 A0 [51] Int. Cl. F02m 39/00 [58] Field of Search 123/139 AP, 139AQ [56] References Cited UNITED STATES PATENTS 2,488,361 11/1949 Witzky 123/139 AQ 2,743,893 5/1956 Bischoff.... 123/139 AQ 2,910,696 10/1959 Heiser 123/139 AQ 2,910,976 11/1959 Fancher 123/139 AQ 2,914,054 11/1959 Deutschmann v. 123/139 AO 3,024,779 3/1962 Hogeman .1 123/139 AQ 3,091,231 5/1963 Giraudon [23/139 A0 3,433,159 3/1969 Kemp 123/139 AQ 3,603,112 /1971 Sola 123/139 AQ Primary ExaminerCharles J. Myhre Assistant Examiner-Ronald E. Cox Attorney, Agent, or Firm-Edwin E. Greigg [57] ABSTRACT In a fuel injection apparatus in which the terminal moment of the injection during each pressure stroke of the pump piston is determined in an engine rpmdependent manner by the position of the governor member of a centrifugal governor, the beginning moment of each injection is determined by a setting mechanism which is responsive to the output pressure of a fuel pump serving the fuel injection apparatus. Said output pressure, in turn, is a function of the position of said governor member.

4 Claims, 2 Drawing Figures FUEL INJECTION APPARATUS FOR INTERNAL COMBUSTION ENGINES BACKGROUND OF THE INVENTION This invention relates to a fuel injection apparatus for internal combustion engines and is of the type that has a fuel injection pump in which the injected fuel quantities are altered by changing the terminal moment of fuel delivery during each pressure stroke of the pump piston. The fuel injection apparatus is coupled to a fuel supply pump, the delivery pressure of which affects, in an rpm-dependent manner, a hydraulic setting device which serves for the adjustment of the moment of injection. The fuel injection apparatus further includes an rpm regulator, the governor member of which serves for the alteration of the injected fuel quantities.

In a fuel injection apparatus of the afore-outlined type the moment of delivery start of the fuel injection pump determining the moment of injection is constant. Stated differently, the moment the injection starts during each pressure stroke of the fuel injection pump does not vary as the injected fuel quantities change. Some engines, however, require that for small injected fuel quantities (partial load conditions) the injection begin at a later moment to cause a delay in the starting moment of injection of the fuel injection pump.

OBJECT AND SUMMARY OF THE INVENTION It is an object of the invention to provide an improved fuel injection apparatus in which the aforeoutlined requirement is met by simple means.

Briefly stated, according to the invention, from the pressure side of the fuel supply pump there extends a channel which is controlled by the governor of the rpm regulator in such a manner that a variable fuel quantity is discharged from the pressure side of the fuel supply pump; in this manner the output pressure of the fuel supply pump is variable.

The invention will be better understood as well as further objects and advantages become more apparent from the ensuing detailed specification of a preferred, although exemplary embodiment taken in conjunction with the drawing.

, BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a sectional view of the fuel injection apparatus incorporating the preferred embodiment and FIG. 2 is a sectional view of some components taken along line lIIl of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to FIG. 1, in a housing 1 of a fuel injection pump serving a multicylinder internal combustion engine (not shown) there is supported a drive shaft 2 coupled with a cam disc 3 which carries as many camming protrusions 4 as there are cylinders in the engine. The track of the cam disc 3 is engaged by rollers, not shown, which are held in a ring 6. The latter is inserted into the pump housing 1 and is rotatable about the axis of the shaft 2 by means of a pin 7 extending into the ring 6. A fuel pumping and distributing member 8 has, at its side adjacent its drive means, a collar 9 which is coupled with the cam disc 3 by means of a pin 10.

On the collar 9 there are disposed in a face-to-face relationship two sliding discs 11 and an upwardly spherical disc 12 against which there is pressed a complemental counter-face of a yoke 13 by means of two axially parallel coil return springs 14 (only one shown) disposed at with respect to the axis of the pump. The return springs 14 engage a pump block 15 which is inserted in a fluid tight manner in an opening of the pump housing 1. Under the effect of the springs 14 the cam disc 3 is continuously pressed against the rollers supported by the ring 6.

The pumping and distributing member 8 is.slidably situated in a cylinder sleeve 17 which is fixedly inserted into the pump block 15. The latter is closed at the top by a threaded cap 19 which presses a valve seat body 20 against the edge face of the cylinder sleeve 17. In an axial bore of the valve seat body 20 there is slidably arranged a movable valve member 21 which, in its closed position, is pressed against the valve seat body 20 by means of a spring 22 seated in a cavity of the closure cap 19.

To the pump shaft 2 there is affixed a rotary positive displacement pump 24 which serves as a fuel supply pump and which delivers fuel directly into the inner chamber 26 formed in the housing 1. From the inner chamber 26 there extends a channel 27 which leads to an inlet channel 28 in the cylinder sleeve 17. The inlet channel 28 cooperates with longitudinal grooves 29 provided in the lateral face of a terminal portion of the pumping and distributing member 8. The longitudinal grooves 29 communicate with a pump work chamber 30 controlled by the pressure valve 20, 21. From the cavity of the threaded cap 19 which is disposed downstream of the valve 20, 21, there extends a channel 31 which passes through the valve seat body 30 and the wall of the cylinder sleeve 17 and which opens into a radial channel 32 provided in the cylinder sleeve 17. The channel 32 cooperates with an annular groove 33 of the pumping and distributing member 8. From the annular chamber 33 there extends, in the pumping and distributing member 8, an axially oriented distributor groove 34 which cooperates with the outlet channels 35 (only one shown). The latter are disposed radially with respect to the cylinder sleeve 17 and in an inclined manner in the pump block 15. They open into threaded coupling outlets 36 to which there are connected injection conduits (not shown) leading to the fuel injection nozzles (also not shown) of the internal combustion engine. Similarly to the camming protrusions 4 of the cam disc 3, the longitudinal grooves 29 and the outlet channels 35 with the coupling outlets 36 are equal in number to that of the cylinders of the internal combustion engine.

In the pumping and distributing member 8 there is provided an axial channel 38 which extends from the pump work chamber 30 to a transversal channel 39. The mouths of the transversal channel 39 in the lateral face of the pumping and distributing member 8 cooperate with a control sleeve 41 which is axially displaceable on the pumping and distributing member 8. For causing an axial displacement of the control sleeve 41, into a depression of the latter there extends a spherical terminus of an arm 42 of a two-arm lever 42, 43 which is pivotally held on a pin 44. The pin 44 is disposed in an eccentric manner on the radial face of a shaft 45 which is supported in the pump housing 1 and which serves for the setting of the full load fuel quantities and for a fuel shut-off.

The other arm 43 of the two-arm lever 42, 43 is engaged by the spherical terminus of a governor member 47 of an rpm regulator which is slidable on a regulator shaft 48 fixedly attached to the housing 1. On the regulator shaft 48 there is rotatably mounted a spur gear 49 which meshes with a spur gear 50 keyed to the pump drive shaft 2. With the spur gear 49 there are fixedly connected sheet metal pockets 51 in which there are supported centrifugal weights 52. Each of the latter engages the governor member 47 by means of an arm 53.

The arm 43 of the two-arm lever 42, 43 is exposed to the force of a compression spring 54 and a tension spring 55 which serve as regulator springs. The compression spring 54 engages directly the lever arm 43 and is supported by a flaring pin 56. Into the pin 56 there is hooked one end of the tension spring 55, the other end of which is in engagement with a pin 57. The latter is affixed to a setting lever 58 which, for the purpose of adjusting the rpm to be regulated, is operable from the outside of the housing 1. The governor member 47 has radial openings 60 which cooperate with an annular groove 61 provided in the lateral face of the regulator shaft 48. The annular groove 61 is in continuous communication with a longitudinal bore 62 which opens into a transversal bore 63, both provided in the regulator shaft 48. The bore 63 is connected, by means of an oblique bore 64, with an inlet bore 65 which joins, in a manner not shown, the suction side of the fuel supply pump 24.

As best seen in FIG. 2, the pin 7 extends with its terminus projecting from the housing 1, into a cylindrical joint 66 which is rotatably arranged in a piston 67 of a hydraulic setting mechanism, the housing 68 of which adjoins the housing 1 of the fuel injection pump (FIG. 1). The piston 67 is exposed to the pressure prevailing in the inner chamber 26 of the housing 1 through a channel 69. The other terminal face of the piston 67 is engaged by a spring 70. The last-named terminal face of the piston 67 is in communication with the intake (low pressure) side of the fuel supply pump 24 through a channel 71.

OPERATION OF THE PREFERRED EMBODIMENT When the internal combustion engine is running, the drive shaft 2 of the fuel injection pump rotates, causing rotation of the cam disc 3 which in cooperation with the rollers of the ring 6 effects an axial reciprocating motion and a simultaneous rotary motion of the pumping and distributing member 8. During this operation the cam disc 3 is maintained in continuous contact with the afore-noted rollers by means of the return springs 14. The pumping and distributing member 8 is shown in FIG. 1 in its lower dead center position. The pump work chamber 30 is charged with fuel through the inlet channel 28. As the cam disc 3 rotates, first the inlet channel 28 is closed by the land of the pumping and distributing member 8. During the immediately following effective pressure stroke of the pumping and distributing member 8, fuel is delivered from the pump work chamber 30 through the open valve 20, 21, the channels 31 and 32 into the annular groove 33 and therefrom through the distributor groove 34 to one of the outlet channels 35 and then to the associated outlet coupling 36. Therefrom the fuel is admitted to the individual fuel injection nozzles of the internal combustion engine.

The fuel supply pump 24 supplies fuel into the inner chamber 26 of the fuel injection pump at an rpmdependent pressure. The pressurized fuel exerts a force on the piston 67 of the hydraulic setting mechanism and thereby angularly adjusts in an rpm-dependent manner the ring 6 through the pin 7. The angular position of the ring 6 determines the beginning of injection start of the fuel injection pump.

As the rpm increases, the centrifugal weights 52 of the centrifugal regulator swing outwardly and displace the governor member 47 upwardly against the force of the regulator springs 54, 55. During this occurrence, first the spring 54 which serves for the regulation of the idling rpm, is compressed and thereafter the spring 55 serving for the regulation of the operational rpm is tensioned. During this displacement of the governor member 47, on the one hand, the control sleeve 41 is shifted downwardly so that the fuel quantities delivered by the fuel injection pump are decreased (partial load) and, on the other hand, the annular groove 61 of the regulator shaft is opened by the bores 60 of the governor member 47 so that fuel may escape from the inner chamber 26 of the pump housing 1 and thus the pressure in the inner chamber 26 is reduced. Consequently, the pressure exerted on the piston 67 also drops which causes a rotation of the ring 6 altering the injection start of the fuel injection pump and thus the duration of injection. In the afore-described example the moment of injection is shifted toward delay.

What is claimed is:

1. In a fuel injection apparatus serving an internal combustion engine, said apparatus being of the known type that has (a) a fuel injection pump delivering fuel quantities to said engine for injection, (b) an rpm regulator having a governor member, (c) means connecting said governor member to said fuel injection pump for varying the terminal moment of injection to vary said fuel quantities, (d) a fuel supply pump connected to said fuel injection pump to supply the latter with fuel, the output pressure of said fuel supply pump being a function of the engine rpm and (e) a hydraulic setting mechanism connected to said fuel injection pump for varying the moment of injection in response to a change in said output pressure, the improvement comprising:

A. a housing, within which elements (a)-(e) are mounted, said housing defining an inner chamber into which fuel is delivered by said fuel supply P p;

B. means extending into said chamber and defining a channel leading from said chamber to the suction side of said fuel supply pump; and

C. means forming part of said governor member, said last named means cooperating with said channel means to change the flow passage section thereof as a function of the position of said governor member for causing a drainage of a variable fuel quantity from said chamber to said suction side of said fuel supply pump for altering the output pressure thereof.

2. An improvement as defined in claim 1, including a support member on which said governor member is slidably mounted, said support member having a lateral face at which said channel means starts, said channel means being controlled by said governor member at said lateral face.

3. An improvement as defined in claim 2, wherein said support member is formed of a fixedly held regulator shaft, said channel means starting on the lateral face of said regulator shaft and extending therethrough.

4. In a fuel injection apparatus serving an internal combustion engine, said apparatus being of the known type that has (a) a fuel injection pump delivering fuel quantities to said engine for injection, (b) an rpm regulator having a governor member, (c) means connecting said governor member to said fuel injection pump for varying the terminal moment of injection to vary said fuel quantities, (d) a fuel supply pump connected to said fuel injection pump to supply the latter with fuel, the output pressure of said fuel supply pump being a function of the engine rpm and (e) a hydraulic setting mechanism connected to said fuel injection pump for varying the moment of injection in response to the change in said output pressure, the improvement comprising:

A. a channel means leading from the delivery side of said fuel supply pump to a location of lesser pressure than prevailing at said delivery side;

B. means forming part of said governor member, said last named means cooperating with said channel means to change the flow passage section thereof as a function of the position of said governor member for causing a drainage of a variable fuel quantity from the delivery side of said fuel supply pump for altering the output pressure thereof;

C. a rotating and reciprocating fuel pumping and distributing member forming part of said fuel injection pump;

D. a pump work chamber forming part of said fuel injection pump and adjoining said fuel pumping and distributing member;

E. a relief channel passing through said fuel pumping and distributing member and communicating with said pump work chamber;

F. a control sleeve mounted on said pumping and distributing member for controlling said relief channel;

G. coupling means for connecting said control sleeve with said governor member, said control sleeve and said coupling means forming part of said means connecting said governor member to said fuel injection pump;

H. a centrifugal governor constituting said rpm regulator;

I. a governor sleeve forming part of said centrifugal governor and constituting said governor member; and

J. a support member on which said governor sleeve is slidably mounted, said support member having a lateral face at which said channel means starts, said channel means being controlled by said governor sleeve at said lateral face. 

1. In a fuel injection apparatus serving an internal combustion engine, said apparatus being of the known type that has (a) a fuel injection pump delivering fuel quantities to said engine for injection, (b) an rpm regulator having a governor member, (c) means connecting said governor member to said fuel injection pump for varying the terminal moment of injection to vary said fuel quantities, (d) a fuel supply pump connected to said fuel injection pump to supply the latter with fuel, the output pressure of said fuel supply pump being a function of the engine rpm and (e) a hydraulic setting mechanism connected to said fuel injection pump for varying the moment of injection in response to a change in said output pressure, the improvement comprising: A. a housing, within which elements (a)-(e) are mounted, said housing defining an inner chamber into which fuel is delivered by said fuel supply pump; B. means extending into said chamber and defining a channel leading from said chamber to the suction side of said fuel supply pump; and C. means forming part of said governor member, said last named means cooperating with said channel means to change the flow passage section thereof as a function of the position of said governor member for causing a drainage of a variable fuel quantity from said chamber to said suction side of said fuel supply pump for altering the output pressure thereof.
 2. An improvement as defined in claim 1, including a support member on which said governor member is slidably mounted, said support member having a lateral face at which said channel means starts, said channel means being controlled by said governor member at said lateral face.
 3. An improvement as defined in claim 2, wherein said support member is formed of a fixedly held regulator shaft, said channel means starting on the lateral face of said regulator shaft and extending therethrough.
 4. In a fuel injection apparatus serving an internal combustion engine, said apparatus being of the known type that has (a) a fuel injection pump delivering fuel quantities to said engine for injection, (b) an rpm regulator having a governor member, (c) means connecting said governor member to said fuel injection pump for varying the terminal moment of injection to vary said fuel quantities, (d) a fuel supply pump connected to said fuel injection pump to supply the latter with fuel, the output pressure of said fuel supply pump being a function of the engine rpm and (e) a hydraulic setting mechanism connected to said fuel injection pump for varying the moment of injection in response to the change in said output pressure, the improvement comprising: A. a channel means leading from the delivery side of said fuel supply pump to a location of lesser pressure than prevailing at said delivery side; B. means forming part of said governor member, said last named means cooperating with said channel means to change the flow passage section thereof as a function of the position of said governor member for causing a drainage of a variable fuel quantity from the delivery side of said fuel supply pump for altering the output pressure thereof; C. a rotating and reciprocating fuel pumping and distributing member forming part of said fuel injection pump; D. a pump work chamber forming part of said fuEl injection pump and adjoining said fuel pumping and distributing member; E. a relief channel passing through said fuel pumping and distributing member and communicating with said pump work chamber; F. a control sleeve mounted on said pumping and distributing member for controlling said relief channel; G. coupling means for connecting said control sleeve with said governor member, said control sleeve and said coupling means forming part of said means connecting said governor member to said fuel injection pump; H. a centrifugal governor constituting said rpm regulator; I. a governor sleeve forming part of said centrifugal governor and constituting said governor member; and J. a support member on which said governor sleeve is slidably mounted, said support member having a lateral face at which said channel means starts, said channel means being controlled by said governor sleeve at said lateral face. 